# Questions tagged [airspeed]

The speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed ("IAS"), calibrated airspeed ("CAS"), true airspeed ("TAS"), equivalent airspeed ("EAS") and density airspeed.

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### How do I find the minimum level flight speed at 0 and 10,000m? [closed]

I have to find the minimum level flight speeds at 0, and 10,000m. From my understanding the minimum speed would be near stalling point(?) I made a graph of the C_l and C_d corresponding to the angle ...
109 views

### is there a way to convert speed into g-force, or do you need acceleration too? [closed]

kind of a stupid question, just wondering.
4k views

### How does it feel like to be outside a flying airplane?

Riding a motorcycle on a freeway at over 200 kph you surely feel the rush of air around you. A typical commercial jet airliner travels at approximately 3-5 times that speed at cruise altitude. ...
138 views

### Why is this equation for TAS only valid for subsonic flow?

I came across the equation for calculating True airspeed (TAS) on Wikipedia: $$\text{TAS} = a_0 \sqrt{\frac{5 T}{T_0} \left[ \left( \frac{q_c}{P} + 1 \right)^{2 / 7} - 1 \right]}$$ But this equation ...
271 views

### Can a slow small plane, flying at a few meters above the ground, drop to the ground if the headwind abruptly stops? [duplicate]

Why do I ask this question? Because Wilbur Wright sent a letter to Georges Spratt (an aviation enthusiast he personally knew) saying that his plane, Flyer II, once in flight, accelerated easily to 45 ...
108 views

### Relation between weight of the aircraft and mach number [closed]

Is there any formula that relates weight of the aircraft with mach number?
131 views

### How did the Wright brothers measure the maximum airspeed of their 1904 plane?

The Wright brothers used during their 1904 trials (105 in total, according with their claims) a Richard anemometer mounted on Flyer II (there are numerous pictures on the net with such a device). The ...
1k views

### The slowest to fastest ratio plane [closed]

What fixed wing, and motor, plane or jet, has the largest range between its minimum and its maximum airspeed by which it can safely fly for prolonged periods?
162 views

### So fast, it melts the ice off?

Approximately, how fast would an aircraft have to travel through freezing air to melt the ice off the wing, propellers, or rotor blades?
160 views

### What equations and constants did they use to build the E6B flight computer?

E6B Flight computer: During my practice test, I tried to use the wikipedia provided equations to calculate Density Altitude and ended up with different results than the E6B. In this case, it looks ...
81 views

### What airspeed is required at sea level to create the same aerodynamic pressure as cruise altitude?

I would like to know what speed would be required, at sea level, to exert the same aerodynamic pressure as experienced at cruise altitude. For example, if an airliner were traveling at 500kn at 35,000'...
264 views

### Why this P-51 limitations placard for diving?

I noticed that this placard has different diving speeds related to altitud. My guess is that those values are a safety speed to prevent going into regions close to Mach 1. I know that the speed of ...
112 views

### What is the required accuracy of an airspeed indicator?

What FAA document specifies the accuracy to which an airspeed indicator must be calibrated to?
409 views

### Could airliners fetch data like AoA and speed from an INS?

If I understood what an inertial navigation system (INS) is, it should be able to calculate speed and orientation of the aircraft. If this is possible, why do airliners solely rely on sensors to ...
643 views

### Why does TAS increase as altitude increases and why does my C-152 POH seem to contradict this?

I remember learning and memorizing that TAS increases as altitude increases, however I don't understand why. Especially since my C-152's PoH seems to indicate the opposite in the cruise performance ...
86 views

### How is airspeed measured on supersonic aircraft? [duplicate]

Behind the shock wave air is subsonic, would that not cause an issue with the pitot tubes or any other sensor?
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### What's the relationship between AOA and airspeed?

We know that any aircraft will stall at its stall speed (for a specific weight, CG position, etc.) but also, that the same airplane will always stall at the same angle of attack. I´ve read that IAS is ...
94 views

### Fighter Jets speed [duplicate]

How does an aircraft measures (or calculates) its speed while in air? Which equipment or sensors are used for measurement of speed? Does it takes Earth as a reference frame for its speed measurement ...
65 views

### Maximum climb angle [duplicate]

I've got this graph of vertical climb rate vs airspeed, and ive been asked to find the maximum climb angle from the graph, but I'm not really sure what part of the curve shows this. I can do the math ...
184 views

### What would cause a non-zero indicated airspeed reading on the ground?

What kind of failure would cause an indicated airspeed of say 200 knots on the ground (stationary)?
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### Why are pitot-static measurements preferred over other velocimetry techniques?

I believe hot wire anemometers (HWA, frequently used in wind tunnels to measure flow velocity) or other sensitive techniques could be used to determine the airspeed. Are there specific reasons for why ...
898 views

### Why do I get an overspeed warning at 250kts below 10,000ft in Microsoft Flight Simulator?

I'm flying the Cessna CJ4. I get overspeed warnings at 250kts when below 10,000ft, and the speed indicator has red lines at 300kts. Are these warnings triggered because it'll damage the plane to go ...
171 views

### How does altitude affect the TAS and thrust of an electric fan powered aircraft?

I'm confused about the relation between IAS, TAS, thrust, and shaft power, for an electric application. Yes, higher air is thinner, and thrust goes down due to higher airspeed. What I've researched ...
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### Is it possible for a plane to accelerate easily from 30 to 45 mph in flight while it struggles to reach 30 mph (the engine runs at constant power)?

In two letters sent to Dr. G. A. Spratt (an aviation enthusiast), Wilbur Wright reported the progress he and his brother had made, up to September 10, 1904, regarding Flyer II, a plane powered by a 16-...
2k views

### Why angle of attack is always shown against the relative wind parallel to horizon?

I have a question about Stall, which I have difficulty to understand. According to the theory, stall happens when : 1- Speed is slow then a certain limit. 2- Angle of attack is greater than a ...
458 views

### Is Ducted fan or Propeller better to maximize forward speed of RC aircraft with a given power?

I'm designing an RC aircraft of which the final goal is a crazy top speed. I'll be 3D printing and sanding / finishing the air frame surfaces to reduce drag. In order to achieve maximum top speed, ...
90 views

### Is propeller wake turbulence quantifiable based on operating conditions?

I know the propeller does work on the air and thus the flow behind a propeller is higher than the airspeed. However, what is the quality of this flow? If I were doing a heat transfer analysis of an ...
284 views

### Why are true and indicated airspeed different?

So, I understand that True air speed is the motion of aircraft relative to air around it. And, indicated airspeed is speed arising due to dynamic pressure. Considering a true airspeed of 100 knots, ...
341 views

### How can the cruise speed be larger than Vne?

I recently read the POH for a M20V, the advertising for this aircraft states that the top speed is 242 KIAS. The POH gives the Vne at 196/195 KCAL/KIAS. I have found a similar discrepancy, the Vl3 (...
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### SR-71 flew 2193 mph. How can this mathematically be Mach 3.3?

Virtually every time I read about the Lockheed SR-71 (including other threads on this forum), I see that its speed record is listed as approximately 2193 mph. The same blurb will invariably say this ...
446 views

### What is CAS and EAS and how to calculate from IAS? [duplicate]

I am trying to understand IAS, CAS, EAS, and TAS. I was under the impression that CAS is IAS corrected for instrumentation error and position error. The error is specific to the type of aircraft. Why ...
260 views

### Why do turbofans go faster than turboprops? [duplicate]

Can someone explain why turboprops are less effective in terms of thrust than turbofans? But at the same time, why turboprops burn less fuel? For example, the Bombardier Q400/De Havilland Dash 8 has a ...
235 views

### What is the Saint-Venant formula for calculating equivalent air speed (EAS)?

I'm studying some ground exams (for a lapsed IR). In the course notes it says that EAS (Equivalent Airspeed, i.e. a compressibility-corrected airspeed) is calculated (e.g. by an aicraft's Air Data ...
157 views

### What is the relation between velocity and rate of pitch?

I saw the answer to airspeed and rate of turn but this I think isn't what I want. I've seen it many times that aircraft will pitch up much slower when at higher speeds particularly fighter aircraft. ...
84 views

### Is it possible to determine if winds were high without groundspeed, wind speed, AoA or AoS?

I have a data set that includes TAS, IAS, GPS Lat/Lon, Inertial Lat/Lon, ENU speed, inertial speeds, attitude, and accelerations. I don't need to know the exact wind speed, and I don't think that's ...
308 views

### What's the relation between TAS and Mach in tropopause?

I understand that TAS decreases with altitude with constant Mach number in troposphere, however I'm not sure what happens in tropospause, as the temperature is constant, however the density is still ...
282 views

### How close is the air resistance or drag force to being proportional to the airspeed squared?

How is the total air resistance force exerted upon a body (aircraft or car) related to its speed relative to air at far away? A simple Newton's force momentum analysis suggests that the force \$F \...
383 views

### Why do gusts change the airspeed during landing, but turning (which changes where the wind is coming from) does not?

As we know it, aircraft are extremely sensitive to gust during its final landing stage. They can lose airspeed if the wind changes to tail, ad thus loose lift or need to adjust their thrust in order o ...
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### Why would 2 aircraft fitted with the P&W PT6 Engine have different top speed?

Why can the Quest Kodiac and Cessna Caravan not exceed 200 knots? PT6 from Pratt and Whitney in other implementations like Epic E1000 and Pilatus PC12 can cruise at over 300 knots. The Kodiac and ...
9k views

### What is the commercial passenger aircraft top speed record?

Aircraft manufacturers claim that commercial passenger aircrafts cruise at the speed of 400-500 knots. But, is the top speed of a commercial passenger aircraft recorded (while in air)? If so, what is ...
381 views

### What is the power curve [closed]

Someone help me understand this thing in a simple way. I understand it helps determine Vx.
102 views

### What plane has the widest range in speed in which it can operate? [duplicate]

What propellor plane, other than planes with vertical takeoff capability, has the largest gap in speed between its slowest stall speed and its maximum airspeed? I am looking for a plane with a short ...
89 views

### Constant turn radius with Δ airspeed and bank

Can someone explain how speed impacts rate of turn and and degree of bank required? I'm trying to understand this practice problem but can't get the concept: Say you have 2 vehicles travelling at ...
432 views

### Does “trimmed for current speed” mean that the plane will do whatever to maintain the current airspeed?

If I understand right, when you are trimmed for current speed, let’s say 290 KTAS, does that mean if airspeed increases to 295, the plane will pitch up to slow it back down? And vice versa for the ...
63 views

### Linking equivalent airspeed with waypoints, altitude, time and speed

Say I want to find out EAS and I'm given a time that a pilot will reach a waypoint that is "X" Nautical Miles away, an altitude & I'm also given a ground speed that is increased by a tailwind. Is ...
295 views

### What are the equation linking static air temperature with true airspeed & altitude?

If I want to calculate static air temperature (OAT), but I'm only given an altitude and a true airspeed. Is there such an equation that relates these principles together. I've had a look at wikipedia ...
4k views

### Why is a 737 Original speed-restricted below 10 kft with inoperative windscreen heating?

According to this page on the 737's operational limitations, the Original 737s (737-100/-200) are limited to 250 KIAS below 10 kilofeet if the windscreen-heating system is inoperative: Anti-Ice & ...
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### Is any device installed on airplane to measure wind speed relative to the ground, and its direction?

A device or tool which can measure actual wind speed to the ground rather than to the airplane. Also a device which detect the wind direction to the plane. The device I meant is something like this ...